squash! v3dv,broadcom/compiler: don't abuse sampler index

For tex instructions that don't have sampler state use backend_flags
instead of sampler index to bind default sampler state.

Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24537>

src/broadcom/compiler/v3d40_tex.c

@@ -229,12 +229,18 @@ v3d40_vir_emit_tex(struct v3d_compile *c, nir_tex_instr *instr)
         assert(instr->op != nir_texop_lod || c->devinfo->ver >= 42);
 
         unsigned texture_idx = instr->texture_index;
-        unsigned sampler_idx = instr->sampler_index;
+
+        /* For instructions that don't have a sampler (i.e. txf) we bind
+         * default sampler state via the backend_flags to handle precision.
+         */
+        unsigned sampler_idx = nir_tex_instr_need_sampler(instr) ?
+                               instr->sampler_index : instr->backend_flags;
 
         /* Even if the texture operation doesn't need a sampler by
          * itself, we still need to add the sampler configuration
          * parameter if the output is 32 bit
          */
+        assert(sampler_idx < c->key->num_samplers_used);
         bool output_type_32_bit =
                 c->key->sampler[sampler_idx].return_size == 32;
 

src/broadcom/compiler/vir.c

@@ -614,6 +614,19 @@ type_size_vec4(const struct glsl_type *type, bool bindless)
         return glsl_count_attribute_slots(type, false);
 }
 
+static enum nir_lower_tex_packing
+lower_tex_packing_cb(const nir_tex_instr *tex, const void *data)
+{
+   struct v3d_compile *c = (struct v3d_compile *) data;
+
+   int sampler_index = nir_tex_instr_need_sampler(tex) ?
+      tex->sampler_index : tex->backend_flags;
+
+   assert(sampler_index < c->key->num_samplers_used);
+   return c->key->sampler[sampler_index].return_size == 16 ?
+      nir_lower_tex_packing_16 : nir_lower_tex_packing_none;
+}
+
 static void
 v3d_lower_nir(struct v3d_compile *c)
 {
@@ -638,13 +651,8 @@ v3d_lower_nir(struct v3d_compile *c)
                         tex_options.swizzles[i][j] = c->key->tex[i].swizzle[j];
         }
 
-        assert(c->key->num_samplers_used <= ARRAY_SIZE(c->key->sampler));
-        for (int i = 0; i < c->key->num_samplers_used; i++) {
-                if (c->key->sampler[i].return_size == 16) {
-                        tex_options.lower_tex_packing[i] =
-                                nir_lower_tex_packing_16;
-                }
-        }
+        tex_options.lower_tex_packing_cb = lower_tex_packing_cb;
+        tex_options.lower_tex_packing_data = c;
 
         NIR_PASS(_, c->s, nir_lower_tex, &tex_options);
         NIR_PASS(_, c->s, nir_lower_system_values);

src/broadcom/vulkan/v3dv_meta_copy.c

@@ -3621,13 +3621,12 @@ build_nir_tex_op_ms_fetch_sample(struct nir_builder *b,
                                  nir_ssa_def *tex_pos,
                                  nir_ssa_def *sample_idx)
 {
-   nir_tex_instr *tex = nir_tex_instr_create(b->shader, 4);
+   nir_tex_instr *tex = nir_tex_instr_create(b->shader, 3);
    tex->sampler_dim = GLSL_SAMPLER_DIM_MS;
    tex->op = nir_texop_txf_ms;
    tex->src[0] = nir_tex_src_for_ssa(nir_tex_src_coord, tex_pos);
    tex->src[1] = nir_tex_src_for_ssa(nir_tex_src_texture_deref, tex_deref);
-   tex->src[2] = nir_tex_src_for_ssa(nir_tex_src_sampler_deref, tex_deref);
-   tex->src[3] = nir_tex_src_for_ssa(nir_tex_src_ms_index, sample_idx);
+   tex->src[2] = nir_tex_src_for_ssa(nir_tex_src_ms_index, sample_idx);
    tex->dest_type = nir_get_nir_type_for_glsl_base_type(tex_type);
    tex->is_array = false;
    tex->coord_components = tex_pos->num_components;

src/broadcom/vulkan/v3dv_pipeline.c

@@ -718,12 +718,12 @@ lower_sampler(nir_builder *b,
    if (texture_idx < 0 && sampler_idx < 0)
       return false;
 
-   /* If we don't have a sampler, we assign it the idx we reserve for this
-    * case, and we ensure that it is using the correct return size.
+   /* If the instruction doesn't have a sampler (i.e. txf) we use backend_flags
+    * to bind a default sampler state to configure precission.
     */
    if (sampler_idx < 0) {
       state->needs_default_sampler_state = true;
-      instr->sampler_index = return_size == 16 ?
+      instr->backend_flags = return_size == 16 ?
          V3DV_NO_SAMPLER_16BIT_IDX : V3DV_NO_SAMPLER_32BIT_IDX;
    }